This undercuts either the APT classification or the identification of the APT with DPRK. It's not as though Sony doesn't have any money; a group that steals money would have stolen some. In that case there would have been some sort of credible trail to follow.

Actually the whole "we don't like movies about Dear Leader" supposed motivation is only superficially reasonable. From the leaked email it's clear that this was a chaotic capricious organization that wouldn't have hesitated to fire embittered IT (or simply IT-aware) staff, who would then have been well-placed to do everything that was done to Sony. (I especially liked the unencrypted Word docs they had of nothing but hundreds of passwords. Passwords don't belong in Word docs!) "Guardians of Peace" had a special hatred for Sony execs, while e.g. Rogen and Franco were afterthoughts.